I also have non-speaking 21mo. Well, he has got about thirty vocab words but no sentences, not even two-word sentences. Not stressin about it, it'll come when he is ready.
So, activities... We don't have any toddler groups near us. DS has a plastic motorbike, he uses that to scoot to the park round the corner, or round the neighbourhood very quiet during the day, and one-way system).
We're lucky enough to live near a beach, so we go there every couple of days. Also the nearest playground has a sandpit.
At home we play with megablocks (running through colours etc), and cars, oh how he loves his cars! He lines them up, they jump over each other, he 'beeps' when he reverses them, he tries identifying colours, big, small etc. We make tunnels and arches with the megablocks.
We do some colouring/crayon time everyday, just A4 paper and scribbling.
He stands on a chair in the kitchen and plays with tupperware/silicon bakeware while I chop veg, or plays with water and bubbles while I'm washing up (stack towels on the floor!).
We lay on our big bed and play 'tickles' (tiled floor throughout house so we can't play rough and tumble on living room carpet!).
We have times set asude for noisy play - drum, xylophone, fisherprice piano-thing.
We put the radio on and dance.
We read/play with books.
He helps me sew by playing with little bits of ribbon and ricrac and strips of fabric.
We go to town on the bus and have a run around some pedestrian areas and squares.
TV is limited to Pocoyo twice a day for about 5 minutes.
We play dressup: my shoes, DH's jumper, hat, my handbag etc.
Anything and everything to entertain him!